Data from: White Syndrome in Acropora muricata: Non-specific bacterial infection and ciliate histophagy

Selective antibiotic treatment of White Syndrome (WS)-affected corals (Acropora muricata) from Fiji was used to identify 3 potential bacterial pathogens of the disease. Interestingly, the suite of bacterial associates of the disease was different to that recently identified using identical primer sets for WS on the GBR and in the Solomon Islands. In addition to the three bacterial pathogenic candidates and as previously shown for WS and more recently for White Band Disease (WBD) in the Caribbean, all samples of the disease were specifically associated with the histophagous ciliate Philaster lucinda. From the pattern of disease progression and histopathology in relation to the selective elimination of microbial groups, we conclude that these ‘white’ diseases are a result of a non-specific bacterial infection and a ‘secondary’ infection by the P. lucinda ciliate. Although we have not observed the initiation of infection, a non-specific, multi-species bacterial infection appears to be a co-requirement for WS lesion progression and we hypothesize that the bacterial infection occurs initially, weakening the defences of the host to predation by the ciliates. Such ciliate histophagy, gives rise to the characteristic white band of denuded coral skeleton that gives these diseases their names. The characteristics of the microbial communities of WBD and WS appear identical, and since the bacterial associates of WS vary geographically (and/or temporally), there appears to be no logical distinction between WS in the Indo-Pacific and WBD in the Caribbean.

本研究通过对斐济海域感染白色综合征 (White Syndrome, WS) 的鹿角杯形珊瑚 (Acropora muricata) 开展选择性抗生素处理，成功筛选出该疾病的3种潜在细菌性致病菌。值得注意的是，本次鉴定出的疾病相关细菌类群，与近期在大堡礁 (Great Barrier Reef, GBR) 及所罗门群岛利用相同引物组开展的WS相关研究结果存在显著差异。除上述3种潜在致病菌外，与此前WS及近期加勒比海地区白带病 (White Band Disease, WBD) 的研究结果一致，所有患病样本均特异性地与噬组织纤毛虫 (Philaster lucinda) 存在关联。结合疾病进展模式与针对微生物类群选择性清除的组织病理学分析，本研究得出结论：此类“白色”疾病由非特异性细菌感染，以及由该纤毛虫引发的“继发性”感染共同导致。尽管本研究未观测到感染的起始过程，但多物种非特异性细菌感染似乎是WS病损进展的必要协同条件；我们据此提出假说：细菌感染首先发生，削弱宿主对纤毛虫捕食的防御能力。这种纤毛虫的噬组织行为会形成裸露珊瑚骨骼的特征性白色条带，这也是此类疾病名称的由来。WBD与WS的微生物群落特征看似一致；且由于WS的相关细菌类群存在地理（和/或时间）分布差异，因此印度-太平洋海域的WS与加勒比海地区的WBD之间，并无合理的区分依据。